Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 18 species, classified in six or seven genus|genera.
The name hamster is derived from the German word Hamster, itself from earlier Old High German|OHG hamustro, from Old Russian|ORuss choměstorǔ, which is either a blend of the root of Russ khomiak "hamster" and a Baltic word (cf. Lithuanian language|Lith staras "hamster") or of Iranian origin (cf. Av hamaēstar "oppressor").
Behavior can vary depending on their environment, genetics, and interaction with people. Because they are easy to breed in captivity, hamsters are often used as lab animals in more economically developed countries. Hamsters have also become established as popular small pets.
Hamsters are crepuscular. In the wild, they burrow underground in the daylight to avoid being caught by predators. Contrary to popular belief they are a nocturnal animal. Their diet contains a variety of foods, including dried food, berries, nuts, fresh fruits and vegetables. In the wild they will eat any wheat, nuts and small bits of fruit and vegetables that they might find lying around on the ground, and will occasionally eat small insects such as small crickets or mealworms. They have elongated fur-lined pouches on both sides of their heads which extend to their shoulders, which they stuff full of food to be brought back to the colony or to be eaten later.